Tire pressures are critical on Touring

<div class='quotetop'>QUOTE(sonny @ Nov 11 2006, 10:09 AM) [snapback]347427[/snapback]</div>

I have had two incidents on the freeway where I had to make emergency stops. The roads were dry but the rear end just swung around and seemed to be out of control. Air pressure was also 40/38 and our 05 Prius has skid control and ABS. After complaining to the dealer about what I considered a dangerous defect, they apparently lowered the pressure to around factory specs. The results in terms of emergency braking is remarkable. I had another incident where I had to do hard braking and the vehicle slowed quickly without the rear end instability. My confidence in the car is restored. I agree that tire pressure is critical to safer emergency braking. It is just not worth the extra mileage if the car looses braking effectiveness. Perhaps all of this is due to the poor performance of Integrity tires, but until I change over to something better I'm a believer in factory air pressure specs.

 

The factory pressure reccomendations are there for a reason, use them...

 

<_< Interesting comments. I just took delivery on my '07 Touring (Saturday 11/11) and upped the pressures to 40/38 same I had run on my '04 for two years. When I checked the pressures after delivery by the Dealer, I found them varied from 32 to 36 and unbalanced from tire to tire.

I miss the MFD colors available on my '04 (Loved the blue), but sure like the factory leather and enhanced resolution of the MFD on the Touring Edition.

 

From my experience, you'll probably find that there really isn't that big a mileage hit from lowering your tire pressures to the manufacturer's recommended values. The big penalty is when you drive a car with under-inflated tires. I've found that the improved handling far outweighs the one or two MPG drop in fuel economy.

 

I used to be a big fan of running my old Integrities at 44/42 and 36/34 (winter only). I recently purchased the Michelins Pilot Exalto A/S and they are also rated max 44psi. After trying 44/42 and 40/38 for a few days I've realized how unstable the rear of the Prius becomes at these pressures with these particular set of tires. I now run them at 38/36 which provides far greater comfort and stability at a minor cost of mpg (-1 to -2).

 

<div class='quotetop'>QUOTE(silentak1 @ Nov 13 2006, 03:38 AM) [snapback]348085[/snapback]</div>

I agree use the pressure that the manual says. What's a few extra mpg for the sake of safety,not wort the risk.
FishHawk

 

<div class='quotetop'>QUOTE(FishHawk @ Nov 13 2006, 06:48 AM) [snapback]348110[/snapback]</div>

I agree that care has to be taken - and rememebr that with higher pressure tires it is worth driving more defensively - keep a larger distance between you and car in front etc

I have gone up a few psi in my touring - getting 49.5 mpg (US) so far on first tank

 

<div class='quotetop'>QUOTE(Charles Suitt @ Nov 11 2006, 04:20 PM) [snapback]347541[/snapback]</div>

Does it really? I've never read this anywhere before, what is the difference in resolution between a touring and a non-touring? I thought they were the same. :huh:

 

<div class='quotetop'>QUOTE(Warwind @ Nov 13 2006, 04:04 PM) [snapback]348473[/snapback]</div>

Me too. Please enlighten us.

 

Sorry... my post could be confusing. The ENHANCED RESOLUTION occurred in the 2006 and 2007 MFD's and not just in the Touring Edition. The 2004 and 2005 gave four color selections (Green, Blue, Gray and Tan) but the 2007 only provides Green and Orange background selections. The resolution is somewhat finer and on the backup camera, the color and resolution are quite good. This change in screen resolution is one of the reasons the 2006 DVD for the NAV system will not work in the 2004 and 2005 NAV systems. I miss my BLUE... Oh, well...

The NAV MAP in the enhanced resolution is cleaner and easier to read.

 

<div class='quotetop'>QUOTE(sonny @ Nov 11 2006, 11:09 AM) [snapback]347427[/snapback]</div>

I am glad I read of your experience with higher tire pressures with your Touring Edition. I just raised my tire pressures to 40/38 on my 2007 Touring Edition, but will be reducing them to the recommended 35/33. With the higher pressures, it did seem that my Prius handled better, but that was probably my imagination. Does your Touring Edition have the Bridgestone Turanza tires as mine does? Where do they come up with these names?

 

<div class='quotetop'>QUOTE(SW03ES @ Nov 11 2006, 06:11 PM) [snapback]347539[/snapback]</div>

nah, why listen to the highly trained, highly paid engineers? Better to take random advice from a web forum.

 

<div class='quotetop'>QUOTE(ConnecticutYankee @ Mar 15 2007, 10:06 AM) [snapback]406133[/snapback]</div>

That is because it probably DID handle better by creating a stiffer sidewall. In autocross racing everyone raises their air pressure then marks the sidewall with chalk so they can measure how much sidewall movement is going on while the work the course.

 

Hi All,

I am a highly trained engineer, but you do not have to listen to me. You will be better off if you do, however.

The reason people pumped their 185 tires up is due to ware. Leave them at factory level and the edges will ware out prematurely (20 to 30 K miles). This has been forgotten lately, with the coments that 42/40 improves mileage. Another reason to do this is better hydroplaining resistance. If your patch is not loaded evenly, the car will hydroplane easier. Ware on the edges tells us that the center of the tire is at a lower patch pressure than the edges.

Last spring my Prius was darting all over the place in strong cross wind gusts at 65 mph. 1/2 a lane worth was a common response of the Prius to a good midwestern broadside gust. I was running factory specified tire pressures.

I also had a problem trying to take a turn to fast. Rather than skid into a nice flat oversteer, the car went crazy, and almost steered itself into the curb on the other side of the next lane over. I do not have VSC.

Enough was enough. I did what people have been recommending on here - go buy the BT-Tech Stiffening plate. Problems solved. Now the car rolls a little, and stays on track when a wind gust hits. Too fast in a turn, and the front end skids flat sideways a foot or so, and continues on with the turn. Just like a front wheel drive car usually does.

The Touring will have this same side-load sensative chasis steering problem. Its the same chasis.

I really do not think Toyota gets this.

Now if running at factory pressure is an acceptable work-around, by all means do not go back to a hazardous situation. But, if you go out and put the BT-Tech stiffening plate on the car, you will have a much safer handling car, and can run tire presures that will result in long tire life for the 185 tires.

The factory pressure might be best for the low profile tires. Nobody has given us ware results for those tires yet, in normal service, or run the glass plate hydroplane test on the Prius Touring.

 

<div class='quotetop'>QUOTE(donee @ Mar 15 2007, 01:09 PM) [snapback]406166[/snapback]</div>

even 42/40 checked and adjusted every other week will do that... :mellow:

 

It could be that with higher pressure you need to increase the difference front-to-rear in order to get the same handling balance that 33/35 gets you. I figure there must be a point of diminishing returns in terms of tire compliance the higher the pressure gets, and the closer you get to that point the less difference that 2psi offset really makes.

So. Who wants to take their Prius out for a day of autocrossing to dial in that tire pressure?

 

Hi donee

QUOTE: " The Touring will have this same side-load sensative chasis steering problem. Its the same chasis. "

Same chassis, BUT, different suspension, different wheels and tires. Having driven my 2004 for over 2 years, I traded it for a 2007 Touring Edition in November. I find the handling noticeably different, more stable in turns and a bit 'firmer.'. As previously posted, I tried 40/38 psi on the Bridgestone Turanzas but definitely did not like the ride and handling, so I've reduced them to 37/35 psi just a couple of pounds more than the Toyota recommended pressures. I have not found the same steering problem I had on my '04.

My 2¢ worth... for the record.

 

<div class='quotetop'>QUOTE(donee @ Mar 15 2007, 12:09 PM) [snapback]406166[/snapback]</div>

Ware did you get that engineering training? To an old retired engineer, your post recalls the old desk sign that said: "Six months ago I couldn't spell ingeneur and now I are one."

 

<div class='quotetop'>QUOTE(brick @ Mar 15 2007, 11:47 AM) [snapback]406190[/snapback]</div>

Don't temp me... My racing buddies are dying to get me out there and sling it around the track. lol

The last event I went to I almost took it out but was worried about any damage I might do to the braking system.